org.jdbi.v3.core.collector

Class BuiltInCollectorFactory

java.lang.Object

org.jdbi.v3.core.collector.BuiltInCollectorFactory

All Implemented Interfaces:

CollectorFactory

public class BuiltInCollectorFactory
extends Object
implements CollectorFactory

Provides Collectors for built in JDK container types.

Supported container types:

• java.util.Optional<T> (throws an exception if more than one row in result)
• java.util.Collection<T>
• java.util.List<T>
• java.util.ArrayList<T>
• java.util.LinkedList<T>
• java.util.Set<T>
• java.util.HashSet<T>
• java.util.SortedSet<T>
• java.util.TreeSet<T>

Supported Map types - for rows mapped to Map.Entry<K, V>

• java.util.Map<K, V>
• java.util.HashMap<K, V>
• java.util.LinkedHashMap<K, V>
• java.util.SortedMap<K, V>
• java.util.TreeMap<K, V>
• java.util.ConcurrentMap<K, V>
• java.util.ConcurrentHashMap<K, V>
• java.util.WeakHashMap<K, V>

Constructor Summary

Constructors

Constructor and Description
BuiltInCollectorFactory()

Method Summary

Modifier and Type	Method and Description
boolean	accepts(Type containerType)
Collector<?,?,?>	build(Type containerType)
Optional<Type>	elementType(Type containerType)
static <K,V,M extends Map<K,V>> Collector<Map.Entry<K,V>,?,M>	toMap(Supplier<M> mapFactory) Returns a Collector that accumulates Map.Entry<K, V> input elements into a map of the supplied type.
static <T> Collector<T,?,Optional<T>>	toOptional() Returns a Collector that accumulates 0 or 1 input elements into an Optional<T>.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BuiltInCollectorFactory

public BuiltInCollectorFactory()

Method Detail

accepts

public boolean accepts(Type containerType)

Specified by:

accepts in interface CollectorFactory

Parameters:

containerType - the container type

Returns:

whether this factory can produce a collector for the given container type.

build

public Collector<?,?,?> build(Type containerType)

Specified by:

build in interface CollectorFactory

Parameters:

containerType - the type of the container

Returns:

a Collector for the given container type.

See Also:

StatementContext.findCollectorFor(Type), JdbiCollectors.findFor(Type)

elementType

public Optional<Type> elementType(Type containerType)

Specified by:

elementType in interface CollectorFactory

Parameters:

containerType - the container type

Returns:

the container element type if it can be discovered through reflection; empty otherwise.

See Also:

StatementContext.findElementTypeFor(Type)

toMap

public static <K,V,M extends Map<K,V>> Collector<Map.Entry<K,V>,?,M> toMap(Supplier<M> mapFactory)

Returns a Collector that accumulates Map.Entry<K, V> input elements into a map of the supplied type. The returned collector will throw IllegalStateException whenever a set of input elements contains multiple entries with the same key.

Type Parameters:

K - the type of map keys

V - the type of map values

M - the type of the resulting Map

Parameters:

mapFactory - a Supplier which returns a new, empty Map of the appropriate type.

Returns:

a Collector which collects map entry elements into a Map, in encounter order.

toOptional

public static <T> Collector<T,?,Optional<T>> toOptional()

Returns a Collector that accumulates 0 or 1 input elements into an Optional<T>. The returned collector will throw IllegalStateException whenever 2 or more elements are present in a stream.

Type Parameters:

T - the collected type

Returns:

a Collector which collects 0 or 1 input elements into an Optional<T>.